The present invention generally relates to accurate time generation, and more specifically, to a system and method for providing accurate time generation in a computing device of a power system.
Electric utility systems or power systems are designed to generate, transmit and distribute electrical energy to loads via a variety of power system elements such as electrical generators, power transformers, power transmission lines, distribution lines, buses and capacitors, to name a few. As a result, power systems are typically monitored and protected using a number of different types of intelligent electronic device(s) (IED) such as protective relays, remote terminal units, power meters, and the like.
For example, protective schemes in conjunction with the protective devices (e.g., protective relays, surge protectors, arc gaps and associated circuit breakers and reclosers) monitor and protect the power system elements from abnormal conditions such as electrical short circuits, overloads, power swings, pole slips, frequency excursions, voltage fluctuations, and the like. During operation, such protective devices act to isolate, or disconnect portions of the power system or power system element(s) (e.g., a generator, transformers, buses, motors, etc.) from the remainder of the power system upon detection of an abnormal condition or fault in one or more power system element(s).
In addition to power system elements and IEDs, power systems include computing devices (e.g., personal computers) to, among other things, monitor the IEDs and provide associated monitoring information to users such as power system operators, power system engineers, etc. Much of the monitoring information requires time-stamping based on accurate time generation. For example, a computing device may be programmed to build a sequence-of-events record of separate events collected from IEDs located in a particular substation. The sequence-of-events record may then be used by power system personnel to reconstruct events leading to a power outage associated with the substation. In that case, knowledge of the exact time of each event is critical.
Internal computing device clocks such as PC clocks are used to time-stamp each event. Unfortunately, computing device clocks tend to be the subject of a certain amount of error or “drift” over time, as well as being subject to power outages and fluctuations. As a result, they may lose their accuracy and may therefore be unable to provide accurate time-stamping for events occurring in the power system.